Multifunctional composite having eco-friendly energy resource-based Anti-icing performance and preparation method therefor

Abstract

The present invention relates to a multifunctional composite having eco-friendly energy resource-based anti-icing performance and a preparation method therefor and, specifically, to a multifunctional composite having excellent self-heating characteristics and radio wave absorption performance by using a GFRP layer including a glass fiber fabric, an epoxy resin, and carbon black, and to a preparation method therefor.

Description

Multifunctional composite material with anti-icing performance based on eco-friendly energy resources and its manufacturing method

[0001] This invention claims the benefit of Korean Patent Application No. 10-2023-0186673, filed with the Korean Intellectual Property Office on December 20, 2023, the entire contents of which are incorporated herein by reference. The present invention relates to a multifunctional composite material with anti-icing properties based on eco-friendly energy resources and a method for manufacturing the same.

[0002]

[0003] When structures such as aircraft are exposed to extreme conditions, their surfaces can become icy, resulting in increased drag, loss of lift, reduced flight performance, and even fatalities. Chemical and mechanical methods are sometimes used to prevent icing on aircraft surfaces. Examples include plasma heating, electric heating, high-temperature air injection, and physical deicing. These technologies require power to maintain a constant temperature and can cause environmental problems. Therefore, environmentally friendly and efficient deicing technologies are urgently needed.

[0004] As solar energy plays a crucial role in addressing climate change, environmentally friendly research, such as photothermal conversion, is gaining attention. In particular, research is underway on photothermal conversion-based de-icing materials for applications not only in aircraft but also in diverse fields such as road construction. However, most de-icing materials are applied in film or coating form, which can be expensive to maintain and lack load-bearing capacity, posing significant limitations for their application to aircraft.

[0005] Meanwhile, stealth technology, which is essential for increasing the survivability of various weapon systems in modern warfare, can be broadly classified into three categories: shaping technology, radar absorbing material (RAM), and radar absorbing structure (RAS).

[0006] Shape design technology is a technology that scatters electromagnetic waves incident on a weapon system in a direction other than the direction in which they were incident, and is the basis of stealth technology. However, due to recent developments in radar technology, there are limits to ensuring the survivability of an aircraft through shape design alone.

[0007] An electromagnetic wave absorbing material has been developed that can be applied to the structural surface of a weapon system in a manner similar to painting to directly absorb electromagnetic waves. However, it has poor durability, so not only does it require periodic maintenance, but it also has the problem of aircraft performance deteriorating due to the weight of the electromagnetic wave absorbing material itself.

[0008] Accordingly, research on electromagnetic wave absorbing structures in which the load-supporting structure itself can absorb electromagnetic waves is being actively conducted, and composite structures are attracting attention as electromagnetic wave absorbing structures.

[0009]

[0010] The problem to be solved by the present invention is to provide a multifunctional composite material having electromagnetic shielding performance in addition to anti-icing performance.

[0011] However, the problems to be solved by the present invention are not limited to the problems mentioned above, and other problems not mentioned can be clearly understood by those skilled in the art from the description below.

[0012]

[0013] According to one aspect of the present invention, a multifunctional composite is provided, comprising: a first glass fiber reinforced plastic (GFRP) layer; and a second GFRP layer laminated on the first GFRP layer, wherein the first GFRP layer comprises glass fiber fabric and epoxy resin, and the second GFRP layer comprises glass fiber fabric, epoxy resin, and carbon black.

[0014] According to one aspect of the present invention, a method for manufacturing a multifunctional composite is provided, comprising: preparing a glass fiber fabric; impregnating the glass fiber fabric with a mixture including an epoxy resin and carbon black to prepare a second GFRP layer; curing the second GFRP layer; impregnating the glass fiber fabric with an epoxy resin to prepare a first GFRP layer; laminating the second GFRP layer on the first GFRP layer to form a laminate; and curing the laminate.

[0015]

[0016] A multifunctional composite material according to one embodiment of the present invention exhibits excellent radio wave absorption performance and superior photothermal conversion properties, enabling self-heating. Since de-icing using light energy is possible without additional equipment, environmentally friendly de-icing that does not cause environmental pollution can be achieved.

[0017] The effects of the present invention are not limited to the effects described above, and effects not mentioned will be clearly understood by those skilled in the art from the present specification and the attached drawings.

[0018]

[0019] Figure 1 is a front view schematically showing a multifunctional composite material according to the present invention.

[0020] Figure 2 is a drawing schematically showing a method for manufacturing a multifunctional composite material according to the present invention.

[0021] Figure 3 is a graph showing the tensile strength and tensile modulus measured and calculated in the GFRP layers of Manufacturing Examples 3 to 5.

[0022] Figure 4 shows the results of measuring the surface temperature over time of the second CFRP layer of Manufacturing Examples 1-1 to 1-3, 2-1 to 2-3, 3-1 to 3-3 and Comparative Manufacturing Examples 1-1 to 1-3.

[0023] Figure 5 is a graph showing the radio wave absorption rate calculated and measured in the multifunctional composite of Example 1.

[0024]

[0025] When a part of this specification is said to "include" a component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise stated.

[0026] Throughout this specification, terms including ordinal numbers, such as "first" and "second," are used to distinguish one component from another and are not limited by the ordinal numbers. For example, within the scope of the invention, the first component may also be referred to as the second component, and similarly, the second component may be referred to as the first component.

[0027] Throughout this specification, when it is said that an element is "on" another element, this includes not only cases where the element is in contact with the other element, but also cases where another element exists between the two elements.

[0028] When explaining in detail the principles of a preferred embodiment of the present invention, if it is determined that a specific description of a related known function or configuration may unnecessarily obscure the gist of the present invention, the detailed description thereof is omitted.

[0029] The configuration of a specific embodiment of the present invention will be described in detail with reference to the attached drawings below.

[0030] A multifunctional composite according to one embodiment of the present invention comprises a first GFRP layer; and a second GFRP layer laminated on the first GFRP layer, wherein the first GFRP layer comprises a glass fiber fabric and an epoxy resin, and the second GFRP layer comprises a glass fiber fabric, an epoxy resin, and carbon black.

[0031] According to one embodiment of the present invention, the epoxy resin may be a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, a bisphenol S type epoxy resin, a novolac type epoxy resin, a cycloaliphatic epoxy resin, a modified epoxy resin, a diglycidyl ether of bisphenol-A (DGEBA), a toughened diglycidyl ether of bisphenol-A (DGEGA) modified resin, a thermoplastic epoxy resin, or a reactive diluent epoxy resin. By using the epoxy resin, a GFRP composite having high mechanical strength and wear resistance can be provided. In addition, the bonding strength with a glass fiber fabric can be improved, and a GFRP composite having excellent chemical resistance, durability, and heat resistance can be provided.

[0032] Figure 1 is a front view schematically showing a multifunctional composite material according to the present invention.

[0033] Referring to FIG. 1, a multifunctional composite (10) according to one embodiment of the present invention includes a first GFRP layer (100) and a second GFRP layer (200). Specifically, the first GFRP layer (100) includes glass fiber fabric and epoxy resin, and the second GFRP layer (200) includes glass fiber fabric, epoxy resin, and carbon black. At this time, the second GFRP layer (200) may be positioned on the first GFRP layer (100).

[0034] A multifunctional composite according to one embodiment of the present invention may further include a curing agent in at least one of the first GFRP layer and the second GFRP layer. Specifically, the curing agent may be an amine-based or anhydride-based agent. By including the curing agent, the heat resistance and chemical resistance of the multifunctional composite may be improved. In addition, a multifunctional composite with excellent strength may be obtained.

[0035] A multifunctional composite according to one embodiment of the present invention may include, as the curing agent, at least one of polyethyleneamine (PEA), isophorone diamine (IPDA), diaminodiphenylmethane (DDM), methylenedianiline (MDA), hexahydrophthalic anhydride (HHPA), and methylenetetrahydrophthalic anhydride (MTHPA). By using the above-described curing agent, the interlayer bonding strength between the first GFRP layer and the second GFRP layer can be improved, and thus the strength of the multifunctional composite can be excellent.

[0036]

[0037] According to one embodiment of the present invention, the carbon black may have a particle size of 10 nm or more and 500 nm or less. Specifically, the particle size may be 10 nm or more and 300 nm or less, 10 nm or more and 100 nm or less, or 10 nm or more and 50 nm or less. The particle size of the carbon black is not limited, but a smaller particle size may be advantageous in terms of dispersibility.

[0038]

[0039] The second GFRP layer included in the multifunctional composite according to one embodiment of the present invention may contain the carbon black in an amount of 0.1 mass% or more and 40 mass% or less, based on the mass of the epoxy resin and the carbon black. Specifically, the content of the carbon black may be 0.1 mass% or more and 40 mass% or less, 1 mass% or more and 35 mass% or less, 1 mass% or more and 30 mass% or less, 3 mass% or more and 40 mass% or less, 3 mass% or more and 35 mass% or less, 5 mass% or more and 30 mass% or less, 6 mass% or more and 40 mass% or less, 6 mass% or more and 35 mass% or less, or 6 mass% or more and 30 mass% or less. The content of the carbon black may be a mass percentage calculated based on the sum of the masses of the epoxy resin and the carbon black. By including the carbon black in the aforementioned range, a multifunctional composite having excellent radio wave absorption performance can be realized. Additionally, due to its superior photothermal conversion properties, it can be self-heating, enabling de-icing using light energy without additional equipment. Furthermore, it can enable environmentally friendly de-icing that does not cause environmental pollution.

[0040]

[0041] According to one embodiment of the present invention, the multifunctional composite material may have a thickness of the first GFRP layer of 0.01 mm to 4.0 mm. Specifically, the thickness of the first GFRP layer may be 0.01 mm to 3.5 mm, 0.01 mm to 3.0 mm, 0.1 mm to 4.0 mm, 0.1 mm to 3.5 mm, 0.1 mm to 3.0 mm, 0.5 mm to 4.0 mm, 0.5 mm to 3.5 mm, 0.5 mm to 3.0 mm, or 0.56 mm to 2.83 mm. By manufacturing the thickness of the first GFRP layer within the above-described range, a multifunctional composite material with excellent strength can be realized.

[0042] In addition, according to one embodiment of the present invention, the thickness of the second GFRP layer may be 0.01 mm to 4.0 mm. Specifically, the thickness of the second GFRP layer may be 0.01 mm to 3.5 mm, 0.01 mm to 3.0 mm, 0.01 mm to 2.5 mm, 0.01 mm to 2.0 mm, 0.1 mm to 4.0 mm, 0.1 mm to 3.5 mm, 0.1 mm to 3.0 mm, 0.1 mm to 2.5 mm, 0.1 mm to 2.0 mm, 0.2 mm to 4.0 mm, 0.2 mm to 3.5 mm, 0.2 mm to 3.0 mm, 0.2 mm to 2.5 mm, 0.2 mm to 2.0 mm, or 0.27 mm to 1.69 mm. By manufacturing the thickness of the second GFRP layer within the above-described range, a multifunctional composite material with excellent self-heating performance can be realized.

[0043] According to one embodiment of the present invention, the thickness ratio of the first GFRP layer and the second GFRP layer may be 0.0025 to 400. Specifically, the thickness ratio of the first GFRP layer and the second GFRP layer may be 0.1 to 400, 0.1 to 200, 0.1 to 100, 0.1 to 50, 0.1 to 30, 0.2 to 400, 0.2 to 200, 0.2 to 100, 0.2 to 50, 0.2 to 30, 0.3 to 400, 0.3 to 200, 0.3 to 100, 0.3 to 50, 0.3 to 30, or 0.3 to 10.5. By manufacturing the thickness ratio of the first GFRP layer and the second GFRP layer within the above-described range, a multifunctional composite material having both excellent strength and self-heating performance can be realized.

[0044] A multifunctional composite material according to one embodiment of the present invention may have a convergence temperature of 85°C or higher as measured by ISO 4892-2. Specifically, according to the provisions of ISO 4892-2, the wavelength band and intensity of light are 340 nm and 0.51 W / m, respectively.2 When the surface temperature is measured by irradiating the light adjusted to the multifunctional composite material, the temperature may be 90°C or higher or 95°C or higher.

[0045]

[0046] According to another aspect of the present invention, a method for manufacturing a multifunctional composite is provided, comprising: preparing a glass fiber fabric; impregnating the glass fiber fabric with a mixture comprising an epoxy resin and carbon black to prepare a second GFRP layer; curing the second GFRP layer; impregnating the glass fiber fabric with an epoxy resin to prepare a first GFRP layer; laminating the second GFRP layer on the first GFRP layer to form a laminate; and curing the laminate.

[0047] According to one embodiment of the present invention, the first GFRP layer and the second GFRP layer may each be formed by laminating one or more sheets of glass fiber fabric impregnated with an epoxy resin or a mixture containing an epoxy resin and carbon black. Specifically, the second GFRP layer may be manufactured by curing a laminate in which multiple sheets of glass fiber fabric impregnated with a mixture containing an epoxy resin and carbon black are laminated, and the second GFRP layer may be laminated on a laminate in which multiple sheets of glass fiber fabric impregnated with an epoxy resin are laminated and then cured together to manufacture a multifunctional composite in which the second GFRP layer is positioned on the first GFRP layer.

[0048] Figure 2 is a drawing schematically showing a method for manufacturing a multifunctional composite material according to the present invention.

[0049] Referring to FIG. 2, in one embodiment of the present invention, a prepared glass fiber fabric (300) is impregnated with a mixture containing an epoxy resin and carbon black. Several sheets of glass fiber fabric (201) impregnated with the mixture of epoxy resin and carbon black are laminated to prepare a glass fiber fabric laminate (210) containing an epoxy resin and carbon black, and the GFRP laminate (210) containing the epoxy resin and carbon black is cured to form a second GFRP layer (200). The prepared glass fiber fabric (300) is impregnated with an epoxy resin. Several sheets of glass fiber fabric (101) impregnated with the epoxy resin are laminated to prepare a glass fiber fabric laminate (110) containing an epoxy resin, and the cured second GFRP layer (200) is laminated on the glass fiber fabric laminate (110) containing the epoxy resin, and then cured together to manufacture a multifunctional composite (10).

[0050]

[0051] According to one embodiment of the present invention, the method for manufacturing the multifunctional composite may be such that the first GFRP layer is cured, the cured first GFRP layer is laminated on the uncured second GFRP layer to form a laminate, and then the laminate is cured. According to another embodiment of the present invention, the uncured first GFRP layer is laminated on the uncured second GFRP layer to form a laminate, and then the laminate is cured. Preferably, the second GFRP layer is cured, the first GFRP layer is laminated on the cured second GFRP layer to form a laminate, and then the laminate is cured. By first curing the second GFRP layer, the carbon black particle concentration of the mixture including the epoxy resin and carbon black included in the second GFRP layer can be maintained.

[0052] According to one embodiment of the present invention, the method of impregnating the glass fiber fabric with an epoxy resin may use a vacuum injection method, a resin injection method, a hand layup, or an autoclave method, and is not limited to the above-described methods.

[0053] According to one embodiment of the present invention, the curing may be performed at a temperature of 60°C to 150°C. Specifically, the curing may be performed at a temperature range of 60°C to 140°C, 60°C to 130°C, 70°C to 150°C, 70°C to 140°C, 70°C to 130°C, 80°C to 150°C, 80°C to 140°C, or 80°C to 130°C.

[0054] According to one embodiment of the present invention, the curing may be performed for a time of 120 to 230 minutes. Specifically, the curing may be performed in a time range of 120 to 230 minutes, 120 to 200 minutes, 120 to 170 minutes, 130 to 230 minutes, 130 to 200 minutes, 130 to 170 minutes, or 140 to 160 minutes. By performing thermal curing in the above-described manner, the epoxy resin can be easily cured. In addition, the interlayer bonding strength can be improved, thereby improving the strength of the multifunctional composite material.

[0055]

[0056] Hereinafter, the present invention will be described in more detail with reference to preferred embodiments. However, the embodiments and experimental examples according to the present invention may be modified in various ways, and the scope of the present invention is not construed as being limited to the embodiments and experimental examples described below. The embodiments and experimental examples in this specification are provided to more fully explain the present invention to those of average skill in the art.

[0057]

[0058] Manufacturing Example 1. Preparation of a mixture of epoxy resin and carbon black and a GFRP layer

[0059] Glass fiber fabric (product name: GEP 118 (Minhu Composite Co., Ltd., Republic of Korea)) was prepared by cutting it into 200 mm wide × 200 mm long pieces.

[0060] 50 g of epoxy resin (product name: KFR-5121 (Kukdo Chemical Co., Ltd., Republic of Korea)) and 21.43 g of carbon black (product name: KFH-9581LV (Birla Carbon Co., Ltd., USA)) were mixed and dispersed using a high-speed mixer (product name: ARM 310 (Thinky, Japan)) at 2000 RPM for 30 minutes. Then, 50 g of a hardener (product name: KFH-9581LV (Kukdo Chemical Co., Ltd., Republic of Korea)) was added to prepare a mixture containing the epoxy resin and carbon black. At this time, the hardener was used according to the ratio with the epoxy resin disclosed by the manufacturer. Thereafter, the glass fiber fabric was impregnated with the mixture containing the epoxy resin and carbon black to prepare a GFRP layer with a size of 200 mm in width × 200 mm in length × 1.08 mm in thickness.

[0061]

[0062] Manufacturing Examples 2 to 5. Preparation of a mixture of epoxy resin and carbon black and a GFRP layer.

[0063] Mixtures and GFRP layers containing epoxy resins and carbon black of Manufacturing Examples 2 to 5 were prepared in the same manner as Manufacturing Example 1, except that the masses of epoxy resin (product name: KFR-5121 (Kukdo Chemical Co., Ltd., Republic of Korea)) and carbon black (product name: KFH-9581LV (Birla Carbon Co., Ltd., USA)) were adjusted as shown in Table 1 below. The carbon black used had a particle size of 20 nm or less.

[0064]

[0065] Mass of epoxy resin (g) Mass of carbon black (g) Thickness of prepared GFRP (mm) Manufacturing example 1503.191.082 Manufacturing example 25012.51.08 Manufacturing example 35021.431.133 Manufacturing example 45001.04 Manufacturing example 5505.561.07

[0066]

[0067] Experimental Example 1. Mechanical Strength Evaluation

[0068] The GFRP layers prepared in Manufacturing Examples 3 to 5 above were cured at 80°C for 30 minutes and then at 130°C for 120 minutes under a pressure of 7 bar, and then cut to 25 mm in width × 250 mm in length with reference to the ASTM D3039 standard. Both ends of the cut GFRP layers were held and pulled at a speed of 2 mm / min to measure the maximum load that occurs when the GFRP layers break. At this time, Equation 1 used to calculate the tensile strength is as follows.

[0069]

[0070]

[0071]

[0072] In the above equation 1, A represents the cross-sectional area of ​​the tensile specimen, and P max refers to the maximum load just before failure.

[0073] In addition, the tensile modulus when the GFRP layer was deformed by 0.1% to 0.3% was calculated using Equations 2 and 3 below.

[0074]

[0075]

[0076]

[0077] In the above equation 2, E represents the tensile modulus and ε represents the strain. △ε represents the change in strain, and since the tensile modulus is to be obtained when the strain is 0.1% to 0.3%, it was calculated as 0.002. △σ was used as the change in stress calculated through equation 3 below.

[0078]

[0079]

[0080]

[0081] In the above equation 3, σ represents stress, P represents the load applied to the tensile specimen, and A represents the cross-sectional area of ​​the tensile specimen. The stress when the GFRP layers of the above manufacturing examples 3 to 5 were deformed by 0.1% and 0.3%, respectively, were calculated to obtain the amount of change in the stress.

[0082] Figure 3 is a graph showing the tensile strength and tensile modulus measured and calculated in the GFRP layers of Manufacturing Examples 3 to 5. The tensile strength is expressed in MPa, and the tensile modulus is expressed in GPa.

[0083] Referring to FIG. 3, it can be seen that the tensile strength of the GFRP layer of Manufacturing Example 3, which contains the largest amount of carbon black, is the lowest, and the tensile strength of the GFRP layer of Manufacturing Example 4, which does not contain carbon black, is the highest. In addition, the GFRP layer of Manufacturing Example 3, which contains the largest amount of carbon black, has the highest tensile modulus, and the GFRP layer of Manufacturing Example 4, which does not contain carbon black, has the lowest tensile modulus. Accordingly, it can be confirmed that the composite including the GFRP of Manufacturing Example 3 can be most suitably used for articles requiring high tensile modulus properties, such as radio wave absorbing structures and heat-resistant parts.

[0084]

[0085] Manufacturing Example 1-1. Manufacturing of the second GFRP layer

[0086] A GFRP laminate was prepared by stacking four GFRP layers prepared in Manufacturing Example 1. The prepared GFRP laminate was cured at 80°C for 30 minutes and then at 130°C for 120 minutes using an autoclave process at a pressure of 7 bar to produce a second GFRP layer.

[0087]

[0088] Manufacturing Examples 1-2 to 1-3, 2-1 to 2-3, 3-1 to 3-3 and Comparative Manufacturing Examples 1-1 to 1-3. Manufacturing of the second GFRP layer

[0089] Except that the type of GFRP layer and the number of laminates used to make the second GFRP layer were adjusted as shown in Table 2 below, the second GFRP layers of Manufacturing Examples 1-2 to 1-3, 2-1 to 2-3, 3-1 to 3-3 and Comparative Manufacturing Examples 1-1 to 1-3 were manufactured using the same method as the manufacturing method of the second GFRP layer of Manufacturing Example 1-1.

[0090]

[0091] Number of GFRP laminates using the second GFRP layer Thickness (mm) Manufacturing example 1-1 Manufacturing example 140.58 Manufacturing example 1-281.08 Manufacturing example 1-3121.69 Manufacturing example 2-1 Manufacturing example 240.57 Manufacturing example 2-281.08 Manufacturing example 2-3121.55 Manufacturing example 3-1 Manufacturing example 340.61 Manufacturing example 3-281.13 Manufacturing example 3-3121.67 Comparative manufacturing example 1-1 Manufacturing example 440.56 Comparative manufacturing example 1-281.04 Comparative manufacturing example 1-3121.54

[0092]

[0093] Experimental Example 2. Evaluation of Photothermal Conversion Characteristics

[0094] The second CFRP layers of the above Manufacturing Examples 1-1 to 1-3, 2-1 to 2-3, 3-1 to 3-3 and Comparative Manufacturing Examples 1-1 to 1-3 were cut to a width of 35 mm × length of 140 mm. Light energy was irradiated onto the second CFRP layers of the above-described Manufacturing Examples 1-1 to 1-3, 2-1 to 2-3, 3-1 to 3-3 and Comparative Manufacturing Examples 1-1 to 1-3 using a xenon lamp. At this time, the light energy was irradiated with a wavelength band and intensity of 340 nm and 0.51 W / m, respectively, with reference to the ISO 4892 regulations. 2 The surface temperature of the composite was measured to compare the photothermal conversion characteristics of the above manufacturing example and manufacturing comparative example.

[0095] Figure 4 shows the results of measuring the surface temperature over time of the second CFRP layer of Manufacturing Examples 1-1 to 1-3, 2-1 to 2-3, 3-1 to 3-3 and Comparative Manufacturing Examples 1-1 to 1-3.

[0096] The convergence values ​​of the temperature measured on the surface of the second CFRP layer of Manufacturing Examples 1-1 to 1-3, 2-1 to 2-3, 3-1 to 3-3 and Comparative Manufacturing Examples 1-1 to 1-3, which can be confirmed through FIG. 4, are shown in Table 3 below.

[0097]

[0098] Convergence temperature (℃) Manufacturing example 1-1100.9 Manufacturing example 1-299 Manufacturing example 1-399.8 Manufacturing example 2-197.9 Manufacturing example 2-296.1 Manufacturing example 2-396.1 Manufacturing example 3-199.6 Manufacturing example 3-298.2 Manufacturing example 3-398 Comparative Manufacturing example 1-182 Comparative Manufacturing example 1-283.1 Comparative Manufacturing example 1-384.6

[0099]

[0100] Through the above table, it can be confirmed that the convergence temperature of Manufacturing Example 1-1 is the highest at 100.9 ℃. Specifically, among Manufacturing Examples 1-1 to 1-3, the convergence temperature of Manufacturing Example 1-1 is the highest at 100.9 ℃, among Manufacturing Examples 2-1 to 2-3, the convergence temperature of Manufacturing Example 2-1 is the highest at 96.1 ℃, and among Manufacturing Examples 3-1 to 3-3, the temperature of Manufacturing Example 3-1 is the highest at 99.6 ℃. Thus, when the content of carbon black is the same, it can be confirmed that the thinner the layer containing carbon black, the better the photothermal conversion characteristics.

[0101] In addition, when comparing Manufacturing Examples 1-1, 2-1, and 3-1, each of which laminated the same number of GFRP layers manufactured in Manufacturing Examples 1 to 3, it can be confirmed that the photothermal conversion characteristics of Manufacturing Example 1-1, which has the lowest carbon black content, are the best. When comparing Manufacturing Examples 1-2, 2-2, and 3-2, or Manufacturing Examples 1-3, 2-3, and 3-3, it can be confirmed that the photothermal conversion characteristics of the Manufacturing Example, which has the lowest carbon black content, are the best.

[0102]

[0103] Experimental Example 3. Evaluation of Radio Wave Absorption Performance

[0104] The dielectric constant at X-band (8.2 GHz to 12.4 GHz) was measured using the GFRP layers of Manufacturing Examples 1 to 4. The GFRP layers prepared in Manufacturing Examples 1 to 4 were cured at 80°C for 30 minutes and then at 130°C for 120 minutes under a pressure of 7 bar, cut to 200 mm wide × 200 mm long, and then the dielectric constant at 10 GHz, which is the median of the X-band, was measured using an X-band transceiver (product name: PCZ-FSMSMC-20R1 (PICOZEN Co., Ltd., Republic of Korea)). The results are shown in Table 4 below.

[0105]

[0106] Measured dielectric constant value (F·m -1 ) Manufacturing example 14.72-j0.32 Manufacturing example 26.05-j1.55 Manufacturing example 311.68-j21.64 Manufacturing example 44.79-j0.07

[0107]

[0108] Using the measured dielectric constant values ​​and Equations 4 to 8 below, the frequency range of radio waves in which the absorption rate of X-band radio waves was 0.9 or higher in Example 10 was calculated.

[0109]

[0110] The absorption rate (A) can be defined by the following equation 4.

[0111]

[0112]

[0113]

[0114] In the above equation 4, Γ represents the incident reflection coefficient, and the incident reflection coefficient (Γ) can be expressed by the following equation 5.

[0115]

[0116]

[0117]

[0118] In the above equation 5, η0 represents the free-space impedance, and Z1 represents the input impedance of the first layer. Here, Z1 is calculated using a recursive function, as shown in equation 6 below.

[0119]

[0120]

[0121]

[0122] The recursive function of the above equation 6 is the impedance of the last layer (Z n+1 ), it is sequentially calculated by considering the characteristic impedance, thickness, and propagation constant of each layer. At this time, the impedance of the last layer reflects the boundary condition of the last layer, and in this experiment, it was calculated assuming complete reflection.

[0123] In the above equation 6, η n and d n represents the characteristic impedance and thickness of the nth layer, respectively. γ n is the propagation constant, η n and γ n is calculated through Equations 7 and 8 below.

[0124]

[0125]

[0126]

[0127]

[0128]

[0129] In the above equations 7 and 8, μ n and ε nrepresents the magnetic permeability and permittivity of the nth layer, respectively, c represents the speed of light, and ω represents the angular frequency of each incident wave. The imaginary unit j mathematically expresses the phase change and attenuation that occur when an electromagnetic wave passes through a medium, and j 2 =-1 is satisfied.

[0130]

[0131] Example 1. Preparation of multifunctional composite materials

[0132] A GFRP laminate was prepared by laminating two GFRP layers prepared in Manufacturing Example 3. The prepared GFRP laminate was cured at 80°C for 30 minutes and then at 130°C for 120 minutes using an autoclave process at a pressure of 7 bar to produce a second GFRP layer.

[0133] The GFRP layers prepared in Manufacturing Example 4 were laminated 21 times to prepare a first GFRP layer, and the cured second GFRP layer was placed on top of the prepared first GFRP layer, and the layers were cured together at 80°C for 30 minutes and then at 130°C for 120 minutes using an autoclave process at a pressure of 7 bar to produce a multifunctional composite.

[0134] The thickness of the first GFRP layer of the manufactured multifunctional composite was 2.83 mm, and the thickness of the second GFRP layer was 0.27 mm.

[0135]

[0136] Using the measured permittivity and Equations 4 to 8, the frequency range of radio waves for which the absorption rate of radio waves is 0.9 or higher for each variable of Example 1 was calculated. The range of the calculated frequency range is shown in Table 5 below.

[0137]

[0138] Frequency range (GHz) with absorption rate of 0.9 or more during X-band radio waves Example 18.2 - 12.36

[0139]

[0140] Figure 5 is a graph showing the radio wave absorption rate calculated and measured in the multifunctional composite of Example 1. The measurement of the radio wave absorption rate was performed by attaching a PEC (Perfect Electrical Conductor) to the bottom of the multifunctional composite of Example 1, and using an X-band transceiver (Product Name: PCZ-FSMSMC-20R1 (PICOZEN Co., Ltd., Republic of Korea)).

[0141] Through Fig. 5, it can be confirmed that the measured values ​​of the radio wave absorption rate of the multifunctional composite of Example 1 have a reflection loss value of -10 dB or less in the range of 8.2 GHz to 12.17 GHz. Through this, it can be seen that the measured range in which 90% of the radio waves are absorbed is almost identical to the calculated range.

[0142]

[0143] [Explanation of symbols]

[0144] 10: Multifunctional composites

[0145] 100: 1st GFRP layer

[0146] 101: Glass fiber fabric impregnated with epoxy resin

[0147] 110: Laminate of glass fiber fabric impregnated with epoxy resin

[0148] 200: 2nd GFRP layer

[0149] 201: Glass fiber fabric impregnated with epoxy resin and carbon black

[0150] 210: Laminate of glass fiber fabric impregnated with epoxy resin and carbon black

[0151] 300: Fiberglass fabric

Claims

1. A first glass fiber reinforced plastic (GFRP) layer; and A multifunctional composite material comprising a second GFRP layer laminated on the first GFRP layer, The above first GFRP layer comprises glass fiber fabric and epoxy resin, A multifunctional composite material, wherein the second GFRP layer comprises glass fiber fabric, epoxy resin and carbon black.

2. In paragraph 1, At least one of the first GFRP layer and the second GFRP layer further comprises a curing agent. Multifunctional composite material.

3. In paragraph 2, The above curing agent comprises at least one of polyethyleneamine (PEA), isophorone diamine (IPDA), diaminodiphenylmethane (DDM), methylenedianiline (MDA), hexahydrophthalic anhydride (HHPA), and methylenetetrahydrophthalic anhydride (MTHPA). Multifunctional composite material.

4. In paragraph 1, A multifunctional composite material, wherein the content of carbon black included in the second GFRP layer is 0.1 mass% or more and 40 mass% or less, based on the mass of the epoxy resin and carbon black.

5. In paragraph 1, The thickness of the first GFRP layer is 0.01 mm to 4.0 mm, A multifunctional composite material, wherein the thickness of the second GFRP layer is 0.01 mm to 4.0 mm.

6. In paragraph 1, A multifunctional composite having a convergence temperature of 85°C or higher as measured by ISO 4892-2.

7. Step of preparing glass fiber fabric; A step of preparing a second GFRP layer by impregnating the glass fiber fabric with a mixture containing epoxy resin and carbon black; A step of curing the second GFRP layer; A step of preparing a first GFRP layer by impregnating the above glass fiber fabric with epoxy resin; A step of forming a laminate by laminating the second GFRP layer on the first GFRP layer; and A step of curing the above laminate; A method for manufacturing a multifunctional composite material according to claim 1, comprising:

8. In paragraph 7, A method for producing a multifunctional composite material, wherein the above curing is performed at a temperature of 50° C. to 150° C. for a time of 120 to 230 minutes.

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